Authorities say there are many fewer illegal immigrants crossing the U.S.-Mexico border than there used to be. It's a significant turn of events. But let's not mistake it for a solution to our immigration problem.

The U.S. Border Patrol recently reported that arrests along the U.S.-Mexico border in the last five months were down 24 percent from the same period last year. From October 2008 to February 2009, the Border Patrol says it arrested 195,399 illegal immigrants. At that rate, the total number of apprehensions by the end of the federal fiscal year could be about 550,000. And that, says the Border Patrol, would be the lowest level of arrests since 1975. Immigration experts say the main reason for the steep drop-off in apprehensions was the terrible U.S. economy, along with stepped-up enforcement at the border.

Ironically, on this side of the border, those two things often work at loggerheads. There is anecdotal evidence that the bad economy is prompting some illegal immigrants who were already living in the United States to return home to Mexico. Construction jobs have dried up. Day laborers report going for weeks without offers of work. Housekeepers and gardeners are losing clients. But at the same time, those who study the border have said for years that increased enforcement actually discourages some people from returning to Mexico because the immigrants assume it will be more difficult to return to the United States.

How can both be true? For starters, illegal immigrants don't fit one profile. If you're middle-aged and have a family that has put down roots here, you are more likely to stay put in the United States and try to ride out the economic storm than if you're single, in your 20s and have nothing to keep you here. Human beings are an unpredictable lot. They make choices for a million different reasons. And that unpredictability is one reason Americans shouldn't jump to the conclusion that our worries are over now that some illegal immigrants are leaving and others have decided not to come at all.

We still have all the same things we had before the economic crisis — a porous border, a vast income disparity between Mexico and the United States, a healthy demand on this side of the border for cheap labor, and a refusal on both sides of the border to take responsibility for the problem.

So we still need comprehensive immigration reform, and we need it soon. Don't forget. When the economy improves, many of the immigrants who went home might just decide to come back.

Reprinted From The San Diego Union-Tribune. Distributed By Creators Syndicate Inc.